Anesthetic composition

ABSTRACT

THIS INVENTION RELATES TO THE NOVEL COMPOUND 1,1,2 TRIFLUORO-2-BROMOETHYL DIFLUOROCHLOROMETHYL ETHER HAVING THE FORMULA CF2CLOCF2CHFBR. THE COMPOUND IS PREPARED THROUGH STEPWISE CHLORINATION AND FLUORINATION REACTIONS STARTING WITH 1,1,2 TRIFLUORO-2-BROMOETHYL METHYL ETHER. THE COMPOUND IS USEFUL AS AN ANESTHETIC AND AS A SOLVENT AND DISPERSANT FOR FLUORINATED MATERIALS.

United States Patent 3,586,724 ANESTHETIC COMPOSITION Ross C. Terrell, Plainfield, N.J., assignor to Air Reduction Company, Incorporated, New York, N.Y.

No Drawing. Original application Mar. 14, 1968, Ser. No. 712,903. Divided and this application Nov. 14, 1969, Ser. No. 871,294

Int. Cl. C07c 43/12 US. Cl. 260-614 1 Claim ABSTRACT OF THE DISCLOSURE This invention relates to the novel compound 1,1,2 trifluoro-Z-bromoethyl difiuorochloromethyl ether having the formula CF CIOCF CHFBr. The compound is prepared through stepwise chlorination and fiuorination reactions starting with 1,1,2 trifluoro-Z-bromoethyl methyl ether. The compound is useful as an anesthetic and as a solvent and dispersant for fluorinated materials.

This application is a division of application Ser. No. 712,903, filed Mar. 14, 1968 and now abandoned.

This invention relates to the compound 1,1,2 trifluoro- 2-bromoethyl difluorochloromethyl ether, its preparation and its use in producing anesthesia in anesthetic susceptible air breathing mammals.

The compound 1,1,2 trifluoro-Z-bromoethyl difiuorochloromethyl ether has the following formula:

It is normally a clear, colorless liquid with a very slight odor. It has the following physical properties: boiling point 81 C.; vapor pressure 95 mm. at 25 C.; specific gravity 1.7; refractive index n 1.3465 and molecular weight 263.5. The compound is nonfiammable, soda lime stable, and is a potent anesthetic for inhalation anesthetic susceptible mammals. The compound is also easily miscible with other organic liquids including fats and oils and has useful solvent properties, for example, as a solvent for fluorinated olefins and other fluorinated materials such as fiuoro waxes. It may be used to prepare pastes and dispersions of such materials useful for coatings and the like and may be used as a degreasing agent.

The compound 1,1,2 trifluoro-2bromoethyl difluorochloromethylether is preferably prepared through the following series of reactions involving the stepwise chlorination and fiuorination of 1,1,2 trifluoro-Z-bromoethyl methyl ether:

The compound 1,1,2 trifluoro-Z-bromoethyl methyl ether is a well known material which can be prepared by reacting methanol CH OH and trifiuorobromoethylene CF CFBr in the presence of dissolved metallic sodium. The reaction is preferably carried out at temperatures below 30 C. in a vessel maintained under a slight positive pressure of nitrogen to prevent the entrance of air. On completion of the reaction the desired 1,1,2 trifluoro-2- bromoethyl methyl ether can be separated from the reaction mass and purified by fractional distillation under reduced pressure.

The 1,1,2 trifluoro-2-bromoethyl methyl ether precursor is then chlorinated to form CCl OCF CHFBr. The chlori nation of CH OCF CHFB1' to form CCl OCF CHFBr should be carried out in either a fully or partially transparent vessel so that photo energy can be supplied to the reaction. Suitable sources of photo energy are incandescent, ultraviolet and fluorescent lamps and even strong sun light. In view of the ready availability, low

3,586,724 Patented June 22., 1971 ice cost and ease of handling of incandescent lamps they are preferred for use as the illumination source.

The chlorination is carried out by bubbling gaseous chlorine into the liquid CH OCF CHFBr while it is strongly illuminated. The chlorine is added at the same rate at which it reacts which can be determined by checking for chlorine vapor in the effluent from the chlorinator. The reaction is exothermic so cooling water should be supplied to the chlorination apparatus to control the reaction. The chlorination can be carried out at any temperature from 15 C. up to the boiling point of the chlorination mixture. Best results are usually found at 25-35 C. where the reaction rate is fast enough and the formation of byproducts does not present a serious problem.

The effluent from the chlorination apparatus should be passed through a water scrubber to dissolve the HCl which is formed. The chlorination should be continued until approximately 2.5 moles of HCl per mole of starting ether are detected by titration of the dissolved I-lCl with a standard base. The extent of the chlorination can be controlled by the amount of chlorine bubbled through the ether and determined by the amount of eflluent HCl. If too little HCl is evolved it indicates that the chlorination products are predominantly the mono or dichloro product. If too much HCl is determined it indicates that polychloro products have been formed or that the ether has decomposed into undesirable chlorinated reaction products.

The lower chlorination products can be separated from the reaction mass by fractional distillation and recycled to the chlorination step in order to raise the yield of the desired product.

Following the chlorination the reaction mass can be separated by fractional distillation or by vapor phase chromatography. If distillation is employed it is recommended that the pressure be reduced in view of the high molecular weight of the product CCl OCF CHFBr. Excessive heating should obviously be avoided in View of the possibility of decomposing the desired product.

The thus prepared CCl OCF CHFBr should then be transferred to a reaction vessel that will not be attacked during the fiuorination reaction. A stainless steel, copper, nickel, or platinum vessel would be quite suitable. A catalyst such as SbCl SnCl or SbF should then be added to the chlorinated starting material before be-' ginning the fiuorination. The fiuorination reaction can be carried out by bubbling agseous HF through the reaction mixture or by adding solid SbF to the mixture.

The fiuorination reaction is preferably carried out at 0 C. Higher or lower temperatures can be employed, however, it has been found that higher temperatures produce undesirable reaction products while lower temperatures cause a slow rate of reaction.

The effluent from the fiuorination apparatus should be passed through a water scrubber to collect the HCl which is formed during the reaction. The amount of HCl formed is equivalent to the number of chlorine atoms exchanged for fluorine. Too little HCl evolved indicates incompleteexchange. Too much HCl indicates either overfluorination or decomposition. The fiuorination should be continued until approximately two moles of HCl are collected for each mole of CCl OCF CHFBr indicating that two chlorine atoms have been exchanged. The preferred site for the fiuorination is on the chlorine substituted methyl group resulting in the formation of CF ClOCF CHFBr. The desired reaction product can be readily separated from the reaction mixture by fractional distillation.

EXAMPLE 1 Synthesis of CH OCF CHFBr Sodium (10 g.) was dissolved in methanol (500 cc.) and CF =CFBr (500 g.) was added slowly with cooling to about 30 C. and stirring. A positive pressure of nitrogen was maintained in the flask so that no air was introduced into the system. On completion of the reaction, the reaction mixture was poured into water and the crude product (540 g.) recovered was fractionally distilled at 100 mm. to yield 475 g., B.P. 36 at 100 mm., n 1.3660. This product was 99% pure and was satisfactory for chlorination.

EXAMPLE 2 Preparation of CCl OCF CHFBr Approximately 1000 grams of CH OCF CHFBr prepared as illustrated in Example 1, were added to a water jacketed chlorinator fitted with a thermometer, a Dry Ice" cold finger type condenser and a fritted glass gas dispersion tube. The reaction was carried out at 25 C. with gaseous chlorine being bubbled through the solution which was exposed to a source of illumination. The efiluent HCl was collected in a scrubber and aliquots were titrated with a standard base. The reaction was continued until 2.4 moles of HCl per mole of ether was titrated. Following the chlorination -887 grams of material were recovered. The composition of the resulting material was determined by vapor phase chromatography and found to be:

Percent CHCl OCF CHFBr 9 CCl-,OCF CHFBr 41 CHCl OCF CFClBr 25 CCl OCF CFClBr 23 Fractional distillation of this mixture gave 169 grams of CCl OCF CHFBr, B.P. 72-75 c. at 50 mm., 1.4325.

Calculated for C HBrCl F O (percent): C, 12.15; H, 0.34; F, 19.2. Found (percent): C, 12.03; H, 0.33; F, 18.88.

EXAMPLE 3 Preparation of CF CloCF CHFBr A l-liter 3-necked stainless steel flask was fitted with a copper Dry Ice cold finger condenser, a stainless steel stirring shaft and gland and a copper gas inlet tube. To the flask there was then added 50 grams of as prepared in Example 2 and 2.5 grams of SbCl HF gas was then slowly bubbled through the stirred mixture which was maintained at C. The reaction was run until 0.4 moles of HCl was collected, as indicated by the titration of the efliuent HCl which was dissolved in water. Following the fluorination 25 grams of material were recovered. Fractional distillation using a 30 x 0.5 cm. column packed with glass helices gave the pure product, B.P. 81 C., n 1.3465.

Calculated for C HBrClF O (percent): C, 13.7; H, 0.38; F, 36.2. Found (percent): C, 13.87; H, 0.40; F, 36.2.

The structure of CF CIOCF CHFBr was determined by elemental analysis and by N.M.R. and infrared spectra.

In order to determine the potency of 1,1,2 trifluoro-Z- bromoethyl difluorochloromethyl ether as an inhalation anesthetic in combination with oxygen a series of tests were carried out on mice. The 1,1,2 trifluoro-2-bromoethyl difluorochloromethyl ether used was at least 99.5% pure as determined by vapor phase chromatography.

Groups of five mice were placed into a jar and exposed to a concentration of 1.25% by volume of After an induction time of 4.3 minutes, which was free of excitation, the mice were anesthetized. During the period of anesthesia the mice showed no change in respiration and no visible untoward effects. A good anesthetic syndrome was produced and the mice were maintained in a light plane of anesthesia. The mice recovered in 1.3 minutes following removal from the jar and showed no after effects.

Groups of five more mice were then given a similar test with 2.5% by volume of the compound. After an induction time of 1.2 minutes an excellent anesthetic syndrome was produced. Anesthesia was deep and relaxation excellent. The respiration and color were normal and no peripheral vasodilation was noted. The induction period was very smooth with no apparent excitation. On removal from the jar the mice fully recovered in 2.5 minutes.

The compound 1,1,2 trifiuoro-Z-bromoethyl difluorochloromethyl ether exhibits excellent anesthetic properties in inhalation anesthetic susceptible mammals. The compound is non-fiammable and soda lime stable. It lends itself to effective use as an inhalant anesthetic in respirable mixtures containing life-supporting concentrations of oxygen. In addition, studies with the agent have shown that it is highly potent, affords good muscular relaxation, is nontoxic, has a high margin of safety, affords rapid induction free of excitation and rapid recovery, and affords ease of control of the level of anesthesia.

The effective amount of CF ClOCF CHFBr to be employed depends on the level of anesthesia to which the mammal is to be brought, the rate at which anesthesia is to be induced, and the length of time over which anesthesia is to be maintained. Volume percentages of in oxygen from a fraction of a percent up to several percent, can be employed. The person controlling the anesthesia can easily regulate the amount of to be used starting with a small amount of the ether and gradually increasing the amount until the desired plane of anesthesia is reached. By then monitoring the physical properties of the mammal, as is the usual procedure, the duration and plane of anesthesia can be readily controlled.

It should be understood that the foregoing disclosure relates only to a preferred embodiment of the invention and that it is intended to cover all changes and modifications of the example of the invention herein chosen for the purpose of the disclosure which does not constitute departure from the spirit and scope of the invention.

I claim:

1. The compound 1,1,2 trifluoro-Z-bromoethyl difluorochloromethyl ether of the formula CF CIOCF CHFBr.

References Cited UNITED STATES PATENTS 3,095,354 6/1963 Larsen et a1. 260-614FX HOWARD T. MARS, Primary Examiner U.S. Cl. X.R. 204-158; 252-121, 364; 424342 

